Generac 6921 vs Simpson MSH3125-S MegaShot

Generac 6921 vs Simpson MSH3125-S MegaShot
Which one should I go for? Have you been in a dilemma and don’t know which one of these gas pressure washers really suits your cleaning chores? Worry no more! Here is a comprehensive genuine review on these two amazing pressure washers to help you make the best choice.

Main features in the Generac 6921 and Simpson MSH3125-S MegaShot gas pressure washers.

To get you started, here is a comparison of these two pressure washers concerning the main features attached to each:

Engine and power

The Generac 6921 (click HERE to check the price on possess an OHV gasoline engine, manufactured by the Generac themselves. The displacement of the engine is 196cc. It is manually started using the recoil starting system. The engine is quite powerful, made from quality materials and thus one of the most reliable around. On the other hand, Simpson MSH3125-S MegaShot (click HERE to check the price on is powered by a Honda GCV 190 OHC engine, designed for a variety of applications. This four-stroke engine has a displacement capacity of 187cc, slightly lower than that of Generac 6921. This engine features a uniblock construction and overhead cam configuration, a design aimed at lowering both the fuel and the oil consumption. Both engines are CARB compliant when it comes to the issue of emissions. The Simpson MegaShot engine is in addition EPA certified to filter the emissions further. In both cases, engine oil is included in the packages.

The power actually defines the performance of any pressure washer. Generac 6921 delivers a maximum water pressure of up to 2500 PSI and a volumetric flow rate of 2.5 GPM (Gallons per minute). At that pressure, this is a residential pressure washer that can give up to 8400 cleaning units. The Simpson MSH3125-S MegaShot gives a better performance than Generac 6921 with a maximum working pressure of 3100 PSI. Equipped with the maintenance free pump, it has a volumetric flow rate of 2.5 GPM. To increase further the pressure at the nozzle, PowerBoost, a new technology is incorporated into the washing system. Pumps used by both pressure washers are of axial cam type.


Under effectiveness, we look into how well these pressure washers are suited to performing the cleaning tasks. The Generac 6921 has several features that make it easy to operate on and achieve the desired water pressure. The engine is coupled to an axial cam pump with easy access hose connections such that one does not need to kneel on the ground to make the required connections. The unit also comes with four nozzle tips; one at 0 degrees, another one at 25 degrees, a 40 degrees one and lastly a quick-click soap nozzle tip. With this, you can effectively choose between the low pressure and high-pressure nozzle according to the nature of the cleaning job. With the oversized never-flat tires, one can take the unit anywhere within the homestead regardless of the terrain. It also has user-friendly controls and offers an ergonomic handle grip to ensure you are Always comfortable and in control while operating the machine. The engine controls are easily accessible and among them are the on/off switch, the fuel shut-off and choke controls. All these features enhance the usage and effectiveness of the machine at large.

With the Simpson MSH3125-S MegaShot, it is made effective in its own ways to deliver to pressures of over 3000 PSI. The Simpson MegaShot’s PowerBoost axial cam pump increases the performance while reducing on the vibrations, the noise, and heat from this pressure washer. With its compact lightweight design, the manoeuvrability of this pressure washer is very desirable. The balanced wheels also increase the mobility further. It comes with five stainless steel quick connect nozzle tips. These colour coded nozzles lets you use the unit for a variety of applications. The pro-style steel spray wand enables a quick change of the nozzles. Also, suited for cold water applications, the flexible non-marring MorFlex hose is equipped with quick connections. The spray gun features an ergonomic design for comfortable use and also has a safety lock-out to prevent it from any accidental activation. Crafted using quality materials, the engine, the pump, and the hoses are meant to last for a long time making the whole unit durable. It is also very easy to install and to operate, making it one of the best for beginners in the world of pressure washing experience.

Positives and the Negatives.

With the Generac 6921, here are some of the things that you are going to enjoy

  • Has a 0.75-gallon detergent tank attached to the unit; hence soap application is easy.
  • At 57lbs. (25.85kg) the unit is lightweight. With the well-designed oversized non-flat wheels, mobility is made easy even when under the rugged terrain.
  • It has four nozzles with quick change features to accommodate various types of work. Among these include the narrow spray nozzle, the low-pressure nozzle, and a 40-degree nozzle.
  • The pressure washer is quite simple to use. The controls are also quite user-friendly

With the Simpson MSH3125-S MegaShot, among the major things you are going to like about this unit are:

  • With the Honda GCV 190 OHC engine, the unit is a powerful one and gives an incredible performance at 3100 PSI and 2.5 GPM water flow. With such power, even the heavy duty tasks are performed with much ease.
  • It has a downstream detergent injection system for an easier use while cleaning. The ease of use is further improved by the ergonomic spray gun with the safety lockout.
  • It is perfectly designed to minimize engine load and deliver a top notch performance.
  • Comes with a maintenance free OEM technology.
  • The unit comes with a pro-style steel spray with multiple quick connect nozzle tips.
  • The entire unit is crafted using quality materials. This does not only mean it gives a superb performance but also increases the durability of the entire machine.


The disadvantages associated with Generac 6921 include the following:

  • With the power delivered by this unit, it is a household grade pressure washer and cannot be used for commercial purposes.
  • This pressure washer does not meet the CARB requirements as far as the emissions are concerned, hence not sold in some places.
  • The unit can have high noise levels at times hence annoying to the user.

With the Simpson MSH3125-S MegaShot, here are a few cons attached to this unit:

  • Many users have reported issues with missing parts in the shipment of the unit.
  • Pumps are usually less durable than the rest of the unit.
  • There are problems with the company’s customer service.
  • The nozzle holder seems not to be as effective as it needs to be.


It’s time to welcome a new dawn in the world of cleaning with the use of the gasoline-powered pressure washers. Although they are not as quiet as their counterparts that are powered by motors, they pack a lot of power. With simple maintenance practices, you will get the machine running through those years as if it was new. Whether it is washing the driveway, cleaning your vehicle, preparing to paint that wall among others, we all agree that you need the right tool. With Generac 6921, enjoy up to pressures of 2500 PSI and a flow rate of 2.5 GPM. With Simpson MSH3125-S MegaShot, enjoy even greater pressures of up to 3100 PSI and a volumetric flow rate of 2.5 GPM. It uses a maintenance free OEM technology making it better than the Generac 6921. Both are quite easy to use, but the Simpson MSH3125-S MegaShot will guarantee you a longer lifetime, as reviewers have it. It is compact pressure washer with the flexibility and power needed for just about any job. Although they do not come without some flaws, we all agree that both products pack a lot of value, and the prices are also agreeable.

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